<template>
	<view>
		<view class="scroll-view-container">
			<!--左侧滑动区域-->
			<scroll-view scroll-y="true" class="left-scroll-view" :style="{height:wh+'px'}">
				<!-- <view class="left-scroll-view-item active">zzzz</view> -->
				<block v-for="(item,i) in cateList" :key="i">
					<view :class="['left-scroll-view-item',i === active ? 'active' : '']"
					@click="activeChanged(i)">{{item.cat_name}}</view>	
				</block>		
			</scroll-view>
			<!--右侧滑动区域-->
			<scroll-view scroll-y="true"  :style="{height:wh+'px'}" :scroll-top="scrollTop">
				<view class="cate-lv2" v-for="(item2,i2) in cateLevel2" :key="i2">
					<!--二级分类的标题-->
					<view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
					<!--当前二级分类下的三级 分类列表-->
					<view class="cate-lv3-list">
						<view class="cate-lv3-item" v-for="(item3,i3) in item2.children" :key="i3"
						@click="gotoGoodsList(item3)">
							<!--三级分类的图片-->
							<image :src="item3.cat_icon"></image>
							<!--三级分类的文本-->
							<text>{{item3.cat_name}}</text>
						</view>
					</view>
				</view>
			</scroll-view>
		</view>
	</view>
</template>

<script>
	export default {
		data() {
			return {
				//当前设备可用的高度
				wh:0,
				cateList:[],
				active: 0 ,//默认的激活项
				//二级分类列表
				cateLevel2:[],
				//滚动条距离顶部 的距离
				scrollTop:0
			};
		},
		onLoad() {
			const sysInfo=uni.getSystemInfoSync()
			// console.log(sysInfo)
			this.wh=sysInfo.windowHeight
			
			this.getCateList()
		},
		methods: {
			//获取分类列表的数据
			async getCateList() {
				const {data: res} = await uni.$http.get('/api/public/v1/categories')
				if(res.meta.status !== 200) return uni.$showMsg()
				this.cateList = res.message
				
				//为二级分类赋值
				this.cateLevel2 = res.message[0].children
			},
			activeChanged(i) {
				this.active=i
				//重新为二级分类赋值
				this.cateLevel2=this.cateList[i].children
				
				this.scrollTop= this.scrollTop === 0 ? 1 :0
			},
			//跳转到商品列表页面
			gotoGoodsList(item) {
				uni.navigateTo({
					url: '/subpkg/goods_list/goods_list?cid=' + item.cat_id
				})
			}
		}	
	}
</script>

<style lang="scss">
.scroll-view-container {
	display: flex;
	
	.left-scroll-view {
		width: 120px;
		
		.left-scroll-view-item {
			background-color: #F7F7F7;
			line-height: 60px;
			text-align: center;
			font-size: 12px;
			
			&.active {
				background-color: #FFFFFF;
				position: relative;
				
				&::before {
					content: '';
					display: block;
					width: 3px;
					height: 30px;
					background-color: #C00000;
					position: absolute;
					top: 50%;
					left: 0;
					transform: translateY(-50%);
				}
			}
		}
	}
}
.cate-lv2-title {
	font-size: 12px;
	font-weight: bold;
	text-align: center;
	padding: 15px 0;
}
.cate-lv3-list {
	display: flex;
	flex-wrap: wrap; //一行装不下 ，自动换行
	
	.cate-lv3-item{
		width: 33.33%;
		display: flex;
		flex-direction: column;//文字和图片纵向显示
		justify-content: center;//横向和纵向都居中
		align-items: center;
		margin-bottom: 10px;
		
		image {
			width: 60px;
			height: 60px;
		}
		text {
			font-size: 12px;
		}
	}
}
</style>
